Brushless DC motor is the use of semiconductor switching devices to achieve electronic reversing, that is, the use of electronic switching devices to replace the traditional contact commutator and brush. The utility model has the advantages of high reliability, no commutation spark and low mechanical noise, and is widely used in high-grade recording block, VCR, electronic instrument and automation office equipment.
Brushless DC motor consists of permanent magnet rotor, multipole winding stator and position sensor. Position sensor According to rotor position change, the current of the stator windings is changed in a certain order (that is, the position of the rotor pole relative to the stator winding is detected, and the position sensor signal is generated at the location of the position, the power switch circuit is controlled by the signal conversion circuit, and the winding current is switched according to certain logic relation). The operating voltage of the stator windings is provided by the electronic switching circuit controlled by the position sensor output.
Position sensor has magnetic-sensitive, photoelectric and electromagnetic type three kinds. A brushless DC motor with a magnetic-sensitive position sensor, and its magnetic sensor components (such as hall element, magnetic-sensitive diode, magnetic-sensitive electrode, magnetic-sensitive resistor or special integrated circuit) are installed on the stator assembly to detect magnetic field changes in the rotation of the permanent magnet and rotor.
Using photoelectric position sensor Brushless DC motor, on the stator components in a certain position to configure the photoelectric sensor components, the rotor is fitted with a matte, light source for light-emitting diodes or small bulbs. When the rotor rotates, the photosensitive components on the stator will be given intermittent pulses in a certain frequency due to the action of the shading plate.